This first image is calles a series cricuit. There is one current going throughout the whole enitre circuit. The voltage remains the same in the whole series circuit. The volatge is the same because there are no resistors.

The second image is called a parallel circuit. In this circuit, the voltage is the same between the two light bulbs. The current is also the same in the circuit. The current (I) is equal to the voltage (V) divided by the risistance (R). Since the voltage and resitance of both light bulbs are the same that means that the current is also the same.

The last image is a complex circuit. In this complex circuit, there is a parallel circuit, and a series circuit. The voltage (V) is not the same in this circuit. The light bulb, that is in series, is brighter than the other two light bulbs that are in the parallel circuit. This is because it has more voltage (V). The two light bulbs ,in the parallel circuit, equal each other in voltage. The current in the parallel circuit is not the same as the current in the series circuit because it has more resistors (light bulbs).